The NIH supports a broad portfolio of research on cannabinoids and the endocannabinoid system. This research portfolio includes some studies utilizing the whole marijuana plant (Cannabis sativa), but most studies focus on individual cannabinoid compounds. Individual cannabinoid chemicals may be isolated and purified from the marijuana plant or synthesized in the laboratory, or they may be naturally occurring (endogenous) cannabinoids found in the body.

Cannabinoids are classified here as:

Phytocannabinoids – cannabinoids found in leaves, flowers, stems, and seeds collected from the Cannabis sativa plant.

Endogenous – cannabinoids made by the body: examples include N-arachidonoylethanolamine or anandamide (AE) or 2-arachidonoylglycerol (2-AG). AE and 2-AG activity can be manipulated by inhibiting their corresponding hydrolases FAAH or MAGL, preventing their degradation.

There is considerable interest in the possible therapeutic uses of marijuana and its constituent compounds (see NIDA's DrugFacts,Is Marijuana Medicine?). In 2015, the NIH developed three reporting categories to describe the research efforts underway to examine the chemical, physiological, and therapeutic properties of cannabinoids and the physiological systems they affect.

Cannabinoid Research reports the total NIH investment in all cannabinoid research including basic research, animal and human preclinical studies, and clinical research. Studies examining cannabis use disorder and societal/health impacts due to changing marijuana laws and policies are also included. Studies examine all classes of cannabinoids (purified, synthetic, endogenous, phytocannabinoids), molecules that modify their concentration or activity (e.g. FAAH inhibitors), as well as the physiological systems they target (e.g. endocannabinoid system).

Cannabidiol Research – subset of the Cannabinoid Research category that reports all NIH projects examining basic, preclinical, and therapeutic properties of CBD.

Therapeutic Cannabinoid Research – subset of the Cannabinoid Research category (above) that reports all NIH projects examining the therapeutic properties of all classes of cannabinoids (purified, synthetic, endogenous, phytocannabinoids).

In fiscal year 2015, the NIH supported 281 projects totaling over $111 million on cannabinoid research. Within this investment, 49 projects ($21 million) examined therapeutic properties of cannabinoids, and 15 projects ($9 million) focused on CBD. Cannabinoid research is supported broadly across NIH Institutes and Centers (ICs), with each IC supporting research specifically focused on the impact of cannabinoids on health effects within their scientific mission. NIH IC investment in each of these categories for fiscal year 2015 is shown below.